In recent years livestock production in developing countries is increasingly dependent on feedstuffs, whereas the importance of grazing is slowly decreasing. Parallel to this trend there is a strong increase in the per caput demand for livestock products related to strong population growth in developing countries and changes in dietary habits.
This report presents long term scenarios describing interactions between livestock, crop production and land use and the possible consequences for the nutrients required for crop production and animal waste. The livestock-crop interactions also play an important role in the emission of atmospheric pollutants. As an example, scenarios of the emission of ammonia (NH3) and nitrous oxide (N2O) from animal excreta and synthetic fertilizers are presented, as well as projections of the emission of methane (CH4) by ruminating animals.
The starting point is the FAO study World Agriculture: Towards 2010. To ensure that the uncertainty in future projections of agricultural production and demand is sufficiently recognized, three different scenarios are developed: a pessimistic, optimistic and medium scenario. The length of the projection period is determined by the human population in developing countries which is expected to stabilize not earlier than the second half of the twenty-first century.
Scenarios are not forecasts of the future. They are tools to analyse consequences of population increase and economic growth, and to study the effectiveness of potential agricultural or environmental strategies or policies. Future work in this field should include comparison of scenarios from different sources. Recently, the Stockholm Environment Institute developed agricultural scenarios for use in the global integrated assessment model IMAGE, a model which is being developed at the National Institute of Public Health and the Environment (RIVM) in the Netherlands. Unfortunately these scenarios were not available in final draft in the period when this report was compiled, but a comparison may reveal certain weaknesses in the different approaches of scenario construction.